1 /* bfdlink.h -- header file for BFD link routines
2 Copyright 1993 Free Software Foundation, Inc.
3 Written by Steve Chamberlain and Ian Lance Taylor, Cygnus Support.
5 This file is part of BFD, the Binary File Descriptor library.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program; if not, write to the Free Software
19 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
24 /* Which symbols to strip during a link. */
27 strip_none
, /* Don't strip any symbols. */
28 strip_debugger
, /* Strip debugging symbols. */
29 strip_some
, /* keep_hash is the list of symbols to keep. */
30 strip_all
/* Strip all symbols. */
33 /* Which local symbols to discard during a link. This is irrelevant
34 if strip_all is used. */
37 discard_none
, /* Don't discard any locals. */
38 discard_l
, /* Discard locals with a certain prefix. */
39 discard_all
/* Discard all locals. */
42 /* These are the possible types of an entry in the BFD link hash
45 enum bfd_link_hash_type
47 bfd_link_hash_new
, /* Symbol is new. */
48 bfd_link_hash_undefined
, /* Symbol seen before, but undefined. */
49 bfd_link_hash_weak
, /* Symbol is weak and undefined. */
50 bfd_link_hash_defined
, /* Symbol is defined. */
51 bfd_link_hash_common
, /* Symbol is common. */
52 bfd_link_hash_indirect
, /* Symbol is an indirect link. */
53 bfd_link_hash_warning
/* Like indirect, but warn if referenced. */
56 /* The linking routines use a hash table which uses this structure for
59 struct bfd_link_hash_entry
61 /* Base hash table entry structure. */
62 struct bfd_hash_entry root
;
63 /* Type of this entry. */
64 enum bfd_link_hash_type type
;
66 /* Undefined and common symbols are kept in a linked list through
67 this field. This field is not in the union because that would
68 force us to remove entries from the list when we changed their
69 type, which would force the list to be doubly linked, which would
70 waste more memory. When an undefined or common symbol is
71 created, it should be added to this list, the head of which is in
72 the link hash table itself. As symbols are defined, they need
73 not be removed from the list; anything which reads the list must
74 doublecheck the symbol type.
76 Weak symbols are not kept on this list.
78 Defined symbols use this field as a reference marker. If the
79 field is not NULL, or this structure is the tail of the undefined
80 symbol list, the symbol has been referenced. If the symbol is
81 undefined and becomes defined, this field will automatically be
82 non-NULL since the symbol will have been on the undefined symbol
84 struct bfd_link_hash_entry
*next
;
85 /* A union of information depending upon the type. */
88 /* Nothing is kept for bfd_hash_new. */
89 /* bfd_link_hash_undefined, bfd_link_hash_weak. */
92 bfd
*abfd
; /* BFD symbol was found in. */
94 /* bfd_link_hash_defined. */
97 bfd_vma value
; /* Symbol value. */
98 asection
*section
; /* Symbol section. */
100 /* bfd_link_hash_indirect, bfd_link_hash_warning. */
103 struct bfd_link_hash_entry
*link
; /* Real symbol. */
104 const char *warning
; /* Warning (bfd_link_hash_warning only). */
106 /* bfd_link_hash_common. */
109 bfd_vma size
; /* Common symbol size. */
110 asection
*section
; /* Symbol section. */
115 /* This is the link hash table. It is a derived class of
118 struct bfd_link_hash_table
120 /* The hash table itself. */
121 struct bfd_hash_table table
;
122 /* The back end which created this hash table. This indicates the
123 type of the entries in the hash table, which is sometimes
124 important information when linking object files of different
127 /* A linked list of undefined and common symbols, linked through the
128 next field in the bfd_link_hash_entry structure. */
129 struct bfd_link_hash_entry
*undefs
;
130 /* Entries are added to the tail of the undefs list. */
131 struct bfd_link_hash_entry
*undefs_tail
;
134 /* Look up an entry in a link hash table. If FOLLOW is true, this
135 follows bfd_link_hash_indirect and bfd_link_hash_warning links to
137 extern struct bfd_link_hash_entry
*bfd_link_hash_lookup
138 PARAMS ((struct bfd_link_hash_table
*, const char *, boolean create
,
139 boolean copy
, boolean follow
));
141 /* Traverse a link hash table. */
142 extern void bfd_link_hash_traverse
143 PARAMS ((struct bfd_link_hash_table
*,
144 boolean (*) (struct bfd_link_hash_entry
*, PTR
),
147 /* Add an entry to the undefs list. */
148 extern void bfd_link_add_undef
149 PARAMS ((struct bfd_link_hash_table
*, struct bfd_link_hash_entry
*));
151 /* This structure holds all the information needed to communicate
152 between BFD and the linker when doing a link. */
156 /* Function callbacks. */
157 const struct bfd_link_callbacks
*callbacks
;
158 /* true if BFD should generate a relocateable object file. */
159 boolean relocateable
;
160 /* true if BFD should generate a shared object. */
162 /* Which symbols to strip. */
163 enum bfd_link_strip strip
;
164 /* Which local symbols to discard. */
165 enum bfd_link_discard discard
;
166 /* The local symbol prefix to discard if using discard_l. */
167 unsigned int lprefix_len
;
169 /* true if symbols should be retained in memory, false if they
170 should be freed and reread. */
172 /* The list of input BFD's involved in the link. These are chained
173 together via the link_next field. */
175 /* If a symbol should be created for each input BFD, this is section
176 where those symbols should be placed. It must be a section in
177 the output BFD. It may be NULL, in which case no such symbols
178 will be created. This is to support CREATE_OBJECT_SYMBOLS in the
179 linker command language. */
180 asection
*create_object_symbols_section
;
181 /* Hash table handled by BFD. */
182 struct bfd_link_hash_table
*hash
;
183 /* Hash table of symbols to keep. This is NULL unless strip is
185 struct bfd_hash_table
*keep_hash
;
186 /* Hash table of symbols to report back via notice_callback. If
187 this is NULL no symbols are reported back. */
188 struct bfd_hash_table
*notice_hash
;
191 /* This structures holds a set of callback functions. These are
192 called by the BFD linker routines. The first argument to each
193 callback function is the bfd_link_info structure being used. Each
194 function returns a boolean value. If the function returns false,
195 then the BFD function which called it will return with a failure
198 struct bfd_link_callbacks
200 /* A function which is called when an object is added from an
201 archive. ABFD is the archive element being added. NAME is the
202 name of the symbol which caused the archive element to be pulled
204 boolean (*add_archive_element
) PARAMS ((struct bfd_link_info
*,
207 /* A function which is called when a symbol is found with multiple
208 definitions. NAME is the symbol which is defined multiple times.
209 OBFD is the old BFD, OSEC is the old section, OVAL is the old
210 value, NBFD is the new BFD, NSEC is the new section, and NVAL is
211 the new value. OBFD may be NULL. OSEC and NSEC may be
212 bfd_com_section or bfd_ind_section. */
213 boolean (*multiple_definition
) PARAMS ((struct bfd_link_info
*,
221 /* A function which is called when a common symbol is defined
222 multiple times. NAME is the symbol appearing multiple times.
223 OBFD is the BFD of the existing symbol. OTYPE is the type of the
224 existing symbol, either bfd_link_hash_defined or
225 bfd_link_hash_common. If OTYPE is bfd_link_hash_common, OSIZE is
226 the size of the existing symbol. NBFD is the BFD of the new
227 symbol. NTYPE is the type of the new symbol, either
228 bfd_link_hash_defined or bfd_link_hash_common. If NTYPE is
229 bfd_link_hash_common, NSIZE is the size of the new symbol. */
230 boolean (*multiple_common
) PARAMS ((struct bfd_link_info
*,
233 enum bfd_link_hash_type otype
,
236 enum bfd_link_hash_type ntype
,
238 /* A function which is called to add a symbol to a set. ENTRY is
239 the link hash table entry for the set itself (e.g.,
240 __CTOR_LIST__). RELOC is the relocation to use for an entry in
241 the set when generating a relocateable file, and is also used to
242 get the size of the entry when generating an executable file.
243 ABFD, SEC and VALUE identify the value to add to the set. */
244 boolean (*add_to_set
) PARAMS ((struct bfd_link_info
*,
245 struct bfd_link_hash_entry
*entry
,
246 bfd_reloc_code_real_type reloc
,
247 bfd
*abfd
, asection
*sec
, bfd_vma value
));
248 /* A function which is called when the name of a g++ constructor or
249 destructor is found. This is only called by some object file
250 formats. CONSTRUCTOR is true for a constructor, false for a
251 destructor. This will use BFD_RELOC_CTOR when generating a
252 relocateable file. NAME is the name of the symbol found. ABFD,
253 SECTION and VALUE are the value of the symbol. */
254 boolean (*constructor
) PARAMS ((struct bfd_link_info
*,
256 const char *name
, bfd
*abfd
, asection
*sec
,
258 /* A function which is called when there is a reference to a warning
259 symbol. WARNING is the warning to be issued. */
260 boolean (*warning
) PARAMS ((struct bfd_link_info
*,
261 const char *warning
));
262 /* A function which is called when a relocation is attempted against
263 an undefined symbol. NAME is the symbol which is undefined.
264 ABFD, SECTION and ADDRESS identify the location from which the
265 reference is made. */
266 boolean (*undefined_symbol
) PARAMS ((struct bfd_link_info
*,
267 const char *name
, bfd
*abfd
,
268 asection
*section
, bfd_vma address
));
269 /* A function which is called when a reloc overflow occurs. NAME is
270 the name of the symbol or section the reloc is against,
271 RELOC_NAME is the name of the relocation, and ADDEND is any
272 addend that is used. ABFD, SECTION and ADDRESS identify the
273 location at which the overflow occurs; if this is the result of a
274 bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
275 ABFD will be NULL. */
276 boolean (*reloc_overflow
) PARAMS ((struct bfd_link_info
*,
278 const char *reloc_name
, bfd_vma addend
,
279 bfd
*abfd
, asection
*section
,
281 /* A function which is called when a dangerous reloc is performed.
282 The canonical example is an a29k IHCONST reloc which does not
283 follow an IHIHALF reloc. MESSAGE is an appropriate message.
284 ABFD, SECTION and ADDRESS identify the location at which the
285 problem occurred; if this is the result of a
286 bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
287 ABFD will be NULL. */
288 boolean (*reloc_dangerous
) PARAMS ((struct bfd_link_info
*,
290 bfd
*abfd
, asection
*section
,
292 /* A function which is called when a reloc is found to be attached
293 to a symbol which is not being written out. NAME is the name of
294 the symbol. ABFD, SECTION and ADDRESS identify the location of
295 the reloc; if this is the result of a
296 bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
297 ABFD will be NULL. */
298 boolean (*unattached_reloc
) PARAMS ((struct bfd_link_info
*,
300 bfd
*abfd
, asection
*section
,
302 /* A function which is called when a symbol in notice_hash is
303 defined or referenced. NAME is the symbol. ABFD, SECTION and
304 ADDRESS are the value of the symbol. If SECTION is
305 bfd_und_section, this is a reference. */
306 boolean (*notice
) PARAMS ((struct bfd_link_info
*, const char *name
,
307 bfd
*abfd
, asection
*section
, bfd_vma address
));
310 /* The linker builds link_order structures which tell the code how to
311 include input data in the output file. */
313 /* These are the types of link_order structures. */
315 enum bfd_link_order_type
317 bfd_undefined_link_order
, /* Undefined. */
318 bfd_indirect_link_order
, /* Built from a section. */
319 bfd_fill_link_order
, /* Fill with a 16 bit constant. */
320 bfd_data_link_order
, /* Set to explicit data. */
321 bfd_section_reloc_link_order
, /* Relocate against a section. */
322 bfd_symbol_reloc_link_order
/* Relocate against a symbol. */
325 /* This is the link_order structure itself. These form a chain
326 attached to the section whose contents they are describing. */
328 struct bfd_link_order
330 /* Next link_order in chain. */
331 struct bfd_link_order
*next
;
332 /* Type of link_order. */
333 enum bfd_link_order_type type
;
334 /* Offset within output section. */
336 /* Size within output section. */
338 /* Type specific information. */
343 /* Section to include. If this is used, then
344 section->output_section must be the section the
345 link_order is attached to, section->output_offset must
346 equal the link_order offset field, and section->_raw_size
347 must equal the link_order size field. Maybe these
348 restrictions should be relaxed someday. */
353 /* Value to fill with. */
358 /* Data to put into file. The size field gives the number
359 of bytes which this field points to. */
364 /* Description of reloc to generate. Used for
365 bfd_section_reloc_link_order and
366 bfd_symbol_reloc_link_order. */
367 struct bfd_link_order_reloc
*p
;
372 /* A linker order of type bfd_section_reloc_link_order or
373 bfd_symbol_reloc_link_order means to create a reloc against a
374 section or symbol, respectively. This is used to implement -Ur to
375 generate relocs for the constructor tables. The
376 bfd_link_order_reloc structure describes the reloc that BFD should
377 create. It is similar to a arelent, but I didn't use arelent
378 because the linker does not know anything about most symbols, and
379 any asymbol structure it creates will be partially meaningless.
380 This information could logically be in the bfd_link_order struct,
381 but I didn't want to waste the space since these types of relocs
382 are relatively rare. */
384 struct bfd_link_order_reloc
387 bfd_reloc_code_real_type reloc
;
391 /* For type bfd_section_reloc_link_order, this is the section
392 the reloc should be against. This must be a section in the
393 output BFD, not any of the input BFDs. */
395 /* For type bfd_symbol_reloc_link_order, this is the name of the
396 symbol the reloc should be against. */
400 /* Addend to use. The object file should contain zero. The BFD
401 backend is responsible for filling in the contents of the object
402 file correctly. For some object file formats (e.g., COFF) the
403 addend must be stored into in the object file, and for some
404 (e.g., SPARC a.out) it is kept in the reloc. */
408 /* Allocate a new link_order for a section. */
409 extern struct bfd_link_order
*bfd_new_link_order
PARAMS ((bfd
*, asection
*));